Around one million children in London will be offered a polio booster vaccine after the virus was detected in sewage samples across the capital, health officials said Wednesday.
"Following the discovery of type 2 vaccine-derived poliovirus in sewage in north and east London," a targetted booster does would be offered to children between one and nine, said a health ministry statement.
The detected levels suggest "that there is some level of virus transmission in these boroughs which may extend to the adjacent areas", said the statement.
The last case of polio in the UK, which can cause paralysis, was in 1984.Oral polio vaccine (OPV) replicates in the gut and can be passed to others through faecal-contaminated water. So, although it will not hurt the vaccinated child, it could infect their neighbours in places where hygiene and immunisation levels are low.
While weaker than wild poliovirus, this variant can cause serious illness and paralysis in people not vaccinated against the disease.